Evidence for the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mo>Θ</mml:mo><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>in the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>γ</mml:mi><mml:mi>d</mml:mi><mml:mo>→</mml:mo><mml:msup><mml:mi>K</mml:mi><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msup><mml:msup><mml:mi>K</mml:mi><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup><mml:mi mat

Nakano, Takashi; Muramatsu, N.; Ahn, D. S.; Ahn, J. K.; Akimune, H.; Asano, Yoshihiro; Chang, W. C.; Daté, S.; Ejiri, H.; Fujimura, H.; Fujiwara, M̄.; Fukui, S.; Hasegawa, H.; Hicks, K.; Horie, K.; Hotta, T.; Imai, K.; Ishikawa, T.; Iwata, T.; Kato, Y.; Kawai, H.; Kim, Z. Y.; Kino, K.; Kohri, H.; Kumagai, N.; Makino, S.; Matsuda, T.; Matsuoka, N.; Matsumura, T.; Mibe, T.; Miyabe, M.; Miyachi, Y.; Niiyama, M.; Nomachi, M.; Ōhashi, Y.; Ohkuma, H.; Ooba, T.; Oshuev, D. S.; Rangacharyulu, C.; Sakaguchi, A.; Shagin, P. M.; Shiino, Y.; Shimizu, A.; Shimizu, H.; Sugaya, Y.; Sumihama, M.; Toi, Y.; Toyokawa, H.; Wakai, A.; Wang, C. W.; Wang, S. C.; Yonehara, K.; Yorita, T.; Yoshimura, Masashi; Yosoi, M.; Zegers, R. G. T.

doi:10.1103/physrevc.79.025210

Cited by 122 publications

(101 citation statements)

References 34 publications

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“…Subsequently, both experiments were able to confirm their initial observations [6][7][8]. Moreover, increasing the statistics of the charge-exchange reaction allowed DIANA to directly estimate the + intrinsic width: 0.4 ± 0.1 MeV [7,8].…”

Section: Introductionmentioning

confidence: 68%

Observation of a narrow baryon resonance with positive strangeness formed inK+Xe collisions

et al. 2014

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The charge-exchange reaction K + Xe → K 0 pXe is investigated using the data of the DIANA experiment. The distribution of the pK 0 effective mass shows a prominent enhancement near 1538 MeV formed by nearly 80 events above the background, whose width is consistent with being entirely due to the experimental resolution. Under the selections based on a simulation of K + Xe collisions, the statistical significance of the signal reaches 5.5σ . We interpret this observation as strong evidence for formation of a pentaquark baryon with positive strangeness, + (uudds), in the charge-exchange reaction K + n → K 0 p on a bound neutron. The mass of the + baryon is measured as m( + ) = 1538 ± 2 MeV. Using the ratio between the numbers of resonant and nonresonant charge-exchange events in the peak region, the intrinsic width of this baryon resonance is determined as ( + ) = 0.34 ± 0.10 MeV.

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Section: Introductionmentioning

confidence: 68%

Observation of a narrow baryon resonance with positive strangeness formed inK+Xe collisions

et al. 2014

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“…Hadrons with strange quarks are produced by photo-production. The LEPS experiment has reported various interesting data whereas the detection area was limited to forward angle [1,2]. The new LEPS2 detectors will cover almost 4π solid angle.…”

Section: Introductionmentioning

confidence: 99%

High time resolution RPCs with different readout geometries

et al. 2012

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We have developed prototype resistive plate chambers (RPCs) for the LEPS2 experiment at SPring-8 in Japan. At LEPS2, RPCs will be used as time-of-flight detectors. The goal is to achieve a time resolution of 50 ps with a readout cell as large as possible. We made several types of RPCs and examined the dependence of time resolution with the size and the shape of the readout cell. We found that the time resolution and the efficiency largely depend on the shape of the readout cell and the position where it is excited. We confirmed that two-ends strip-shaped readout cells performed better than one-end readout cells, and a promising time resolution of 60 ps was obtained with a 2.5 cm (wide) × 108 cm (long) readout.

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“…More recently a new experiment was done at LEPS on a deuteron target, with more statistics, and a clear peak was observed around 1526 MeV in the K þ n invariant mass distribution [4]. Yet, the experiment of [5] dealing with the same reaction as in LEPS but with 10 times more statistics and with complete kinematics (but excluding small angles), failed to see any peak around the Â þ region.…”

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confidence: 99%

“…In order to understand what is behind the peak seen in [4], we have constructed a theoretical model which contains the basic ingredients seen in the LEPS experiment, production on the proton and the neutron and Ãð1520Þ production on the proton, together with rescattering of the kaons. The details of this model can be seen in [6].…”

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confidence: 99%

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Novel Interpretation of the “Θ+(1540)Pentaquark” Peak

Torres

Oset

2010

Phys. Rev. Lett.

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We use a theoretical model of the γd→K+ K- np reaction adapted to the experiment done at LEPS where a peak was observed and associated with the Θ+ (1540) pentaquark. The study shows that the method used in the experiment to assign momenta to the undetected proton and neutron, together with the chosen cuts, necessarily creates an artificial broad peak in the assumed K+ n invariant mass in the region of the claimed Θ+ (1540), such that the remaining strength seen for the experimental peak is compatible with a fluctuation of 2σ significance.

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Evidence for theΘ+in theγd→K+K−

Cited by 122 publications

References 34 publications

Observation of a narrow baryon resonance with positive strangeness formed inK+Xe collisions

Observation of a narrow baryon resonance with positive strangeness formed inK+Xe collisions

High time resolution RPCs with different readout geometries

Novel Interpretation of the “Θ+(1540)Pentaquark” Peak

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